' © 2015 by Zardoz
 
Private Type XFORM
  eM11 As Single
  eM12 As Single
  eM21 As Single
  eM22 As Single
  eDx As Single
  eDy As Single
End Type
 
Private Declare Function GetWorldTransform Lib "gdi32" (ByVal hdc As Long, _
  lpXform As XFORM) As Long
Private Declare Function SetGraphicsMode Lib "gdi32" (ByVal hdc As Long, ByVal _
iMode As Long) As Long
Private Declare Function SetWorldTransform Lib "gdi32" (ByVal hdc As Long, _
lpXform As XFORM) As Long
 
Private Const GM_ADVANCED = 2
Private Const GM_COMPATIBLE = 1
 
Private Const Pi As Single = 3.141593
 
Private Sub Form_Activate()
 
  Dim x1!, y1!, x2!, y2!, Amplitude!, Frequence%
 
  Me.ScaleMode = vbPixels
  Me.WindowState = vbMaximized
  DoEvents
  With Picture1
    .ScaleMode = vbPixels
    .Move 0, 0, 1000, 700
    .BackColor = vbBlack
    .AutoRedraw = True
  End With
 
  x1 = 50
  y1 = 600
  x2 = 700
  y2 = 100
  Amplitude = 220
  Frequence = 3
  Call DrawSinus(x1, y1, x2, y2, Frequence, Amplitude)
 
End Sub
 
Private Sub DrawSinus(ByVal x1 As Single, ByVal y1 As Single, _
  ByVal x2 As Single, ByVal y2 As Single, _
  ByVal Frequence As Single, ByVal Amplitude As Single)
 
  Dim XP!, YP!, Wnk!, DX!, DY!, S!
  Dim OldMatrix As XFORM
  Dim NewMatrix As XFORM
 
  DX = x2 - x1
  DY = y2 - y1
  Wnk = AtnExt(DX, DY)
  S = Sqr(DX * DX + DY * DY)
 
  With NewMatrix
    .eM11 = Cos(Wnk)
    .eM12 = Sin(Wnk)
    .eM21 = -.eM12
    .eM22 = .eM11
    .eDx = x1
    .eDy = y1
  End With
 
  With Picture1
    Call GetWorldTransform(.hdc, OldMatrix)
    Call SetGraphicsMode(.hdc, GM_ADVANCED)
    Call SetWorldTransform(.hdc, NewMatrix)
 
    .CurrentX = 0
    .CurrentY = 0
 
    For XP = 0 To S - 1
 
      Wnk = XP / S * 2 * Pi * Frequence
      YP = -Amplitude / 2 * Sin(Wnk)
      Picture1.Line -(XP, YP), vbWhite
 
    Next XP
 
    Call SetWorldTransform(.hdc, OldMatrix)
    Call SetGraphicsMode(.hdc, GM_COMPATIBLE)
  End With
 
End Sub
 
Private Function AtnExt(ByVal DX As Single, ByVal DY As Single) As Single
  ' erweiterte Atn-Funktion
 
  Dim Wnk!, ArcTan!
 
  If DX = 0 Then
    ArcTan = 0
  Else
    ArcTan = Atn(Abs(DY / DX))
  End If
 
  If DX = 0 Then
    If DY = 0 Then
      Wnk = 0
    ElseIf DY > 0 Then
      Wnk = Pi / 2
    Else
      Wnk = 3 * Pi / 2
    End If
  ElseIf DX > 0 Then
    If DY < 0 Then
      Wnk = 2 * Pi - ArcTan
    Else
      Wnk = ArcTan
    End If
  Else
    If DY < 0 Then
      Wnk = ArcTan + Pi
    Else
      Wnk = Pi - ArcTan
    End If
  End If
  AtnExt = Wnk
 
End Function

Gruss,

Zardoz